Republican presidential candidate Newt Gingrich is seeking to reduce expectations that he will win the Iowa caucuses as his momentum stalls in national polls.

The former speaker yesterday also sharpened his criticism of former Massachusetts Governor Mitt Romney to blunt a barrage of negative ads Romney’s backers have unleashed against him.

“I never said I’d come in first in Iowa,” Gingrich told reporters at a rally in Virginia that drew only a couple of dozen people to a Richmond-area hotel ballroom. “There was a period when I was the front-runner, but frankly, if you get $7 million or $9 million of ads — most of them false — the sheer weight of negativity has a real impact.”

The two front-runners are keeping up their campaigning today, underscoring the competitiveness of the race even as the pace began to ease for the Christmas holiday weekend.